HK1222153B - Duplex thermal printing system with pivotable diverter - Google Patents

Description

Dual-sided thermal printing system with pivotable diverter

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of us 14/070,496 filed on 11/2/2013, which is a partial continuation of us 13/532,865 (us 8,599,229) and us 13/532,875 (us 8,599,230), both filed on 26/6/2012. United states application number 14/070,496 further claims priority to united states provisional application number 61/867,243 and united states provisional application number 61/867,253, both filed on 8/19/2013.

The present application further claims the benefit of us 14/070,495 application filed on 11/2/2013, which is a partial continuation of us application nos. (us 8,599,229) and 13/532,875 (us 8,599,230), both filed on 26/6/2012. United states application number 14/070,495 further claims priority to united states provisional application number 61/867,243 and united states provisional application number 61/867,253, both filed on 8/19/2013.

Technical Field

The present invention relates to the field of thermal printing systems, and more particularly to a web fed thermal printing system that provides duplex images.

Background

In thermal dye sublimation printing, it is generally well known to render an image by heating one or more donor materials, such as a colorant (e.g., dye) or other coating, and pressing the donor material against a receptor medium having a colorant-receiving layer. Heat is typically supplied by a thermal print head having an array of heating elements. The donor material is typically provided in a sized donor sheet on a movable web called a donor tape. The donor patches are organized on the strip into donor groups; each group contains all of the donor sheets used to record an image on the receptor web. For full-color images, multi-color dye patches, such as red, magenta, and cyan donor dye patches, may be used. Other color chip arrangements may be used in a similar manner within the donor set. Further, each donor set may comprise an overcoat or sealant layer.

Thermal printers offer a wide variety of advantages in photographic printing, including the provision of true continuous tone scale variations and the ability to deposit a protective overcoat as part of the printing process to protect the images formed thereby from mechanical and environmental damage. Accordingly, many photo kiosks and home photo printers currently use thermal printing technology.

Some thermal printing systems are adapted to print on individual sheets of receptor media. Thermal printing systems for high volume applications (e.g., photo booths) typically utilize a web to transport the receiver media. This minimizes the amount of interaction required by the human operator and increases system robustness.

Conventionally, thermal printers are adapted for producing single-sided images and use a receptor medium having a colorant-receiving layer coated on only one side of a substrate. There are various applications (e.g., photo albums and photo calendars) where printing on both sides of a receptor medium may be required to provide a two-sided image. Some prior art methods utilize two printing stations, each containing its own thermal print head and donor tape, each used to print each side of the image. This adds significant cost and size to the thermal printer design. Other prior art methods utilize large and bulky mechanisms to reposition the receiver media supply roll after the first side image has been printed in order to print the second side image. This approach also adds significant cost and size to the thermal printer design.

There is a need for a low cost, compact roll fed duplex thermal printer.

Disclosure of Invention

An embodiment of the present invention provides a roll-fed duplex thermal printing system, comprising: a supply roll of thermal imaging receiver having a dye-receiving layer on a first side and a second side of a substrate; a print path; a reverse path; a pivotable diverter; a thermal print head positioned along a print path; a donor band; a cutter; and a printer controller. The diverter is adapted to pivot about an axis into a first position, a second position, and a third position, wherein the thermal imaging receiver is directed from the supply spool into the print path when the diverter is in the first position, the thermal imaging receiver is directed from the supply spool into the reversing path when the diverter is in the second position, and the thermal imaging receiver is directed from the reversing path into the print path when the diverter is in the third position. The donor ribbon is transported from a donor supply roll to a donor take-up roll by a thermal print head and comprises one or more donor sheets, each having a respective donor material. The cutter is positioned between the diverter and the reverse path. Finally, the printer controller controls the components of the thermal printing system to perform the printing operation.

In an embodiment of the invention, the printer controller controls and directs components of the printing system to perform the following printing process steps: positioning a commutator into a first position; transporting a thermal imaging receiver from a supply spool into a printing path such that a first side of the thermal imaging receiver is oriented to face a thermal print head; moving the thermal imaging receiver and the donor ribbon past a thermal print head during which the thermal print head applies a heat pulse to transfer colorant from the donor ribbon to the first side of the thermal imaging receiver to print a first side image; rewinding the thermal imaging receiver onto the supply spool; pivoting the commutator about the axis to reposition it into the second position; transporting the thermal imaging receiver from the supply roll into the reverse path; using a cutter to cut a portion of the thermal imaging receiver containing the printed first side image from the supply roll; rewinding an uncut portion of the thermographic receptor onto a supply roll; pivoting the commutator about the axis to reposition it into a third position; transporting the cut thermal imaging receiver into a printing path such that a second side of the thermal imaging receiver is oriented to face a thermal print head; moving the cut thermal imaging receiver and the donor ribbon past a thermal print head during which the thermal print head applies a heat pulse to transfer colorant from the donor ribbon onto the second side of the thermal imaging receiver to print a second side image; and transporting the cut thermal imaging receiver out of the printing system.

In some embodiments, the cutter is used to trim one or more end portions from the cut thermographic receptor after the first side image and the second side image have been printed.

The invention has the following advantages: it has reduced costs relative to a duplex printing system that uses two thermal print heads or a compound steering mechanism to reposition a supply roll of a thermal imaging receiver.

The present invention has the following additional advantages: arcuate printing and a reverse path may be used to provide a reduced printer size.

The invention has the following further advantages: a single cutter may be used to both cut and trim the thermal imaging media, saving the cost of the second cutter mechanism.

Drawings

FIG. 1 shows a system diagram of an exemplary thermal printing system;

FIG. 2 is a diagram showing a bottom view of a thermal printhead;

FIG. 3A is a diagram illustrating a donor strip having four different donor patches;

FIGS. 3B through 3C illustrate a printing operation;

FIG. 4 is a diagram illustrating components of a thermal printing system;

FIG. 5 is a diagram illustrating a dual-sided thermal printing system using two thermal print heads;

FIG. 6 is a diagram illustrating an alternative duplex thermal printing system including a steering mechanism for repositioning a receiver supply roll;

FIG. 7 is a diagram illustrating an alternative duplex thermal printing system using a turning roll;

FIG. 8 is a diagram illustrating a duplex thermal printing system according to a preferred embodiment;

FIG. 9 is a flowchart showing steps for controlling the dual-sided thermal printing system of FIG. 8 to provide dual-sided printing;

10A-10I show the dual-sided thermal printing system of FIG. 8 at various stages of a dual-sided printing process;

FIG. 11 is a diagram illustrating a duplex thermal printing system according to an alternative embodiment;

FIG. 12 is a diagram illustrating a dual-sided thermal printing system including several optional features; and

fig. 13A-13G illustrate a variety of different commutator configurations.

It is to be understood that the drawings are for purposes of illustrating the concepts of the invention and are not necessarily drawn to scale.

Detailed Description

The invention includes combinations of the embodiments described herein. References to "a particular embodiment" and the like refer to features that are present in at least one embodiment of the invention. Separate references to "an embodiment" or "particular embodiments" or the like do not necessarily refer to the same embodiments; however, such embodiments are not mutually exclusive unless so indicated or readily apparent to those of ordinary skill in the art. The use of the singular or plural in referring to "a method" or "each method" is not limiting. It should be noted that, unless the context clearly indicates or requires otherwise, in the present invention, the word "or" is used in a non-exclusive sense.

FIG. 1 shows a system diagram of an exemplary thermal printer 18 according to the present invention. As shown in fig. 1, the thermal printer 18 has a printer controller 20 that causes the thermal print head 22 to record an image onto a receiver medium 26 by applying heat and pressure to transfer material from a donor ribbon 30 to the receiver medium 26. The receptor medium 26 comprises a dye-receiving layer coated on a substrate. As used herein, the term "receptor medium" is used synonymously with the terms "thermal imaging receptor" and "thermal medium". Similarly, the term "donor band" is used synonymously with the terms "thermal donor" and "donor web".

The printer controller 20 may include, but is not limited to: a programmable digital computer, a programmable microprocessor, a programmable logic controller, a series of electronic circuits reduced to the form of an integrated circuit, or a series of discrete components. In the embodiment of fig. 1, printer controller 20 also controls receptor drive roller 42, receptor supply spool 44, donor tape take-up spool 48, and donor tape supply spool 50; each of which is motorized to rotate under the command of the printer controller 20 to effect movement of the receptor medium 26 and the donor tape 30.

FIG. 2 shows a bottom view of one embodiment of a typical thermal printhead 22 having an array of thermal resistors 43 fabricated in a ceramic substrate 45. A heat sink 47, typically in the form of an aluminum backplate, is secured to one face of the ceramic substrate 45. The heat sink 47 quickly dissipates heat generated by the heat resistor 43 during printing. In the embodiment shown in fig. 2, the thermal resistors 43 are arranged in a linear array extending across the width of the platen roller 46 (shown in phantom). This linear arrangement of thermal resistors 43 is commonly referred to as a thermal row or print row. However, other non-linear arrangements of the thermal resistor 43 may be used in various embodiments. Furthermore, it will be appreciated that there are a wide variety of other arrangements of thermal resistors 43 and thermal print heads 22 that may be used in conjunction with the present invention.

The thermal resistor 43 is adapted to generate heat proportional to the amount of electrical energy passing through the thermal resistor 43. During printing, the printer controller 20 transmits a signal to a circuit board (not shown) that connects the heat resistors 43, causing different amounts of electrical energy to be applied to the heat resistors 43 to selectively heat the donor ribbon 30 in a manner intended to cause donor material to be applied to the receptor medium 26 in a desired manner.

As shown in fig. 3A, donor ribbon 30 includes: a first donor sheet set 32.1 having a yellow donor sheet 34.1, a magenta donor sheet 36.1, a cyan donor sheet 38.1 and a transparent donor sheet 40.1; and a second set of donor sheets 32.2 having a yellow donor sheet 34.2, a magenta donor sheet 36.2, a cyan donor sheet 38.2, and a transparent donor sheet 40.2. Each donor sheet set 32.1 and 32.2 has a sheet set leading edge L and a sheet set trailing edge T. To provide a full color image with a clear protective coating, four sheets of a donor sheet set are printed in registration with each other onto a common image receiving area 52 of receiver medium 26, as shown in fig. 3B. Printer controller 20 (FIG. 1) provides a variable electrical signal to thermal resistors 43 (FIG. 2) in thermal printhead 22 based on input image data to print an image onto receiver medium 26. As the receiver medium 26 and donor tape move from right to left, each color is printed in turn, as seen by the viewer in fig. 3B.

During printing, printer controller 20 raises thermal print head 22 and actuates donor ribbon supply spool 50 (fig. 1) and donor ribbon take-up spool 48 (fig. 1) to advance leading edge L of first donor sheet set 32.1 to thermal print head 22. In the embodiment illustrated in fig. 3A-3C, leading edge L of first donor sheet set 32.1 is the leading edge of yellow donor sheet 34.1. As will be discussed in more detail below, the location of this leading edge L may be determined by: using a position sensor to detect an appropriate mark or indicia on donor strip 30 having a known position relative to the leading edge of yellow donor sheet 34.1; or directly detect the leading edge of the yellow donor sheet 34.1.

Printer controller 20 also actuates receiver drive roller 42 (fig. 1) and receiver supply spool 44 (fig. 1) so that image receiving area 52 of receiver medium 26 is positioned relative to thermal print head 22. In the illustrated embodiment, image receiving area 52 is defined by a receiving area leading edge LER and a receiving area trailing edge TER on receiver medium 26. Donor ribbon 30 and receiver medium 26 are positioned such that the donor sheet leading edge LED of yellow donor sheet 34.1 is aligned with the receiving area leading edge LER of image receiving area 52 at thermal print head 22. The printer controller 20 then causes a motor or other conventional structure (not shown) to lower the thermal print head 22 so that the lower surface of the donor tape 30 engages the receiver medium 26 supported by the platen roller 46. This creates a pressure that holds donor tape 30 against receptor medium 26.

Printer controller 20 then actuates receptor drive roller 42 (fig. 1), receptor supply spool 44 (fig. 1), donor tape take-up spool 48 (fig. 1), and donor tape supply spool 50 (fig. 1) to move receptor medium 26 and donor tape 30 together past thermal print head 22. At the same time, printer controller 20 selectively operates thermal resistors 43 (fig. 2) in thermal printhead 22 to transfer donor material from yellow donor sheet 34.1 to receiver medium 26.

As the donor tape 30 and receiver medium 26 exit the thermal print head 22, a peeling member 54 (FIG. 1) separates the donor tape 30 from the receiver medium 26. The donor tape 30 continues past idler roller 56 (fig. 1) and toward the donor tape winding reel 48. As shown in fig. 3C, printing continues until the receiving area trailing edge TER of the image receiving area 52 of receiver media 26 touches the print ribbon between thermal print head 22 and platen roller 46. The printer controller 20 then adjusts the position of the donor ribbon 30 and receiver medium 26 using the predefined movement pattern so that the leading edge of each of the next donor sheet in the first donor sheet set 32.1 (i.e., magenta donor sheet 36.1) begins to align with the receiving area leading edge LER of the image receiving area 52, and repeats the printing process to transfer more material to the image receiving area 52. This process is repeated for each donor sheet to form a complete image.

Returning to the discussion of FIG. 1, the printer controller 20 operates the thermal printer 18 based on input signals from: a user input system 62, an output system 64, a memory 68, a communication system 74, and a sensor system 80. User input system 62 may include any form of transducer or other device capable of receiving input from a user and converting this input into a form usable by printer controller 20. For example, the user input system 62 may include a touch screen input, a touchpad input, a 4-way switch, a 6-way switch, an 8-way switch, a light pen system, a trackball system, a joystick system, a voice recognition system, a gesture recognition system, or other such user input systems. An output system 64, such as a display or speaker, is optionally provided and may be used by the printer controller 20 to provide human-perceptible signals (e.g., visual or audio signals) for feedback, informational, or other purposes.

Data including, but not limited to, control programs, digital images, and metadata may also be stored in the memory 68. The memory 68 may take many forms and may include, but is not limited to, conventional memory devices, including solid state, magnetic, optical or other data storage devices. In the FIG. 1 embodiment, memory 68 is shown having a removable memory interface 71 for communicating with removable memory (not shown), such as a magnetic disk, optical disk or magnetic disk. The memory 68 is also shown as having a hard drive 72 fixed with the thermal printer 18 and a remote memory 76 external to the printer controller 20 (such as a personal computer, computer network, or other imaging system).

In the embodiment shown in fig. 1, the printer controller 20 interfaces with a communication system 74 to communicate with external devices, such as a remote memory 76. The communication system 74 may include, for example, a wired or wireless network interface that may be used to receive digital image data and other information and instructions from a host or a network (not shown).

The sensor system 80 includes circuitry and systems adapted to detect conditions within the thermal printer 18 and optionally in the environment surrounding the thermal printer 18, and convert this information into a form that can be used by the printer controller 20 in managing printing operations. The sensor system 80 may take a variety of forms depending on the type of media therein and the operating environment in which the thermal printer 18 is to be used.

In the embodiment of fig. 1, sensor system 80 includes an optional donor position sensor 82 adapted to detect the position of donor ribbon 30 and an acceptor position sensor 84 adapted to detect the position of acceptor medium 26. Printer controller 20 cooperates with the donor position sensor 82 to monitor the donor tape 30 during movement of the donor tape 30 so that printer controller 20 can detect one or more conditions on the donor tape 30 and indicative of the leading edge of the group of donor sheets. Thus, donor band 30 may be provided with markings or other optically, magnetically or electrically sensible markings between each group of donor sheets (e.g., group of donor sheets 32.1) or between donor sheets (e.g., donor sheets 34.1, 36.1, 38.1 and 40.1). In the case where such marks or indicia are provided, donor position sensor 82 is provided to sense such marks or indicia and provide a signal to controller 20. Printer controller 20 may use such markings or indicia to determine when donor ribbon 30 is positioned with the leading edge of the group of donor sheets at thermal print head 22. In a similar manner, the printer controller 20 may use signals from the receptor position sensor 84 during printing to monitor the position of the receptor media 26 to align the receptor media 26. Receptor position sensor 82 may be adapted to sense markers or other optically, magnetically or electrically sensible indicia between each image receiving area of receptor medium 26.

During a full image printing operation, printer controller 20 causes donor ribbon 30 to advance in a predefined distance pattern in order to cause the leading edge of each of the donor sheets (e.g., donor sheets 34.1, 36.1, 38.1, and 40.1) to be accurately positioned relative to image-receiving area 52 at the beginning of each printing process. The printer controller 20 may optionally be adapted to achieve this positioning by: the movement of the donor tape 30 is precisely controlled using a stepper-type motor for motorized donor tape take-up reel 48 or donor tape supply reel 50; or a movement sensor 86 that can detect movement of the donor tape 30. In one example, a driven pulley 88 is provided that engages and moves with donor tape 30. Driven wheel 88 may have surface features that are optically, magnetically, or electrically sensed by movement sensor 86. In one embodiment, driven wheel 88, having indicia thereon indicating the extent of movement of donor tape 30 and movement sensor 86, includes a light sensor that can sense light reflected by the indicia. In other optional embodiments, perforations, cuts, or other conventional yet detectable markings may be incorporated onto the donor tape 30 in a manner that enables the movement sensor 86 to provide an indication of the extent of movement of the donor tape 30.

Optionally, the donor position sensor 82 may be adapted to sense the color of the donor sheet on the donor strip 30 and may provide a color signal to the controller 20. In this case, printer controller 20 may be programmed or otherwise adapted to detect the color of a first donor sheet known to be present in the set of donor sheets (e.g., yellow donor sheet 34.1 in set of donor sheets 21.1). Upon detecting color, the printer controller 20 may determine that the donor ribbon 30 is positioned next to the beginning of the set of donor sheets.

A schematic diagram showing additional details of the components of a thermal printing system 400 according to one embodiment is shown in fig. 4. The donor tape supply roll 50 supplies the donor tape 30. The donor tape winding reel 48 receives used donor tape 30. The receiver supply roll 44 supplies receiver media 26. The receptor medium 26 and the donor tape 30 are merged together between the platen roller 46 and the thermal print head 22, the thermal print head 22 including a heat sink 90 and a peeling member 92. After the thermal print head 22 transfers the donor material from the donor ribbon 30 to the receiver medium 26, the peeling member 92 separates the donor ribbon 30 from the receiver medium 26. Donor ribbon 30 continues to travel onto donor ribbon take-up spool 48 while receptor medium 26 travels between pinch roller 94 and micro-pinch roller 96 to form a nip.

There are many applications that may require images to be printed on both sides of receiver medium 26. For example, photo calendars and photo album pages typically have photos or other content (e.g., text and graphics) printed on both sides of each page. To print a two-sided thermal print, the receptor medium 26 should have a dye receiving layer coated on both sides of the substrate. Various arrangements may then be used to transfer the dye to both sides of the receptor medium 26.

Fig. 5 shows one arrangement that may be used for a duplex thermal printing system 410. In this configuration, the primary printing components shown in the arrangement of fig. 4 are duplicated, with one primary printing component arranged to print on each side of the receptor 26. The first thermal print head 22A transfers dye from the first donor ribbon 30A to a first side of the receiver medium 26, and the second thermal print head 22B transfers dye from the second donor ribbon 30B to a second side of the receiver medium 26. This configuration has the following advantages: the duplex image can be printed without a complicated sheet processing mechanism. The main drawback of this approach is that it adds significant cost to the printer, as it doubles the number of thermal print heads 22A and 22B and other associated components. The method also requires a longer media path and therefore increases the printer size accordingly. Another disadvantage is that two spools of donor tape 30A and 30B must be used, which means that the printer operator will need to stack a larger number of spools, and if the donor tapes 30A and 30B are used at different rates, it may require more frequent maintenance of the printer to reload the donor tape when one of the spools is depleted.

Fig. 6 shows another arrangement that may be used for a duplex thermal printing system 420. In this configuration, which is similar to that used in the KODAKD400 Duplex Photo Printer, the recipient supply spool 44 is provided with a steering mechanism (not shown) that enables it to pivot from a first position 422 to a second position 424. With the receiver supply spool 44 in the first position 422, the printing system configuration is similar to that shown in fig. 4. After the first side of the image has been printed using the thermal print head, receiver media 26 will be rewound onto receiver supply roll 44. The receiver supply spool 44 is then pivoted into the second position 424 and the receiver media 26 is again passed between the thermal print head 22 and the platen roller 46. The opposite side of the receiver medium will now face the thermal print head 22 so that the second side of the image can be printed. The main disadvantage of this approach is that the steering mechanism of the receptor supply roll 44 adds significant cost to the printer. Because the recipient supply spool 44 is typically quite large relative to the printer size, the printer size must also be increased to provide space to position the recipient supply spool 44 into the second position 424.

FIG. 7 shows an embodiment of a dual-sided thermal printing system 430 including a turning mechanism for turning the receiver media 26 over. In this configuration, a cutter 432 is provided that can be used to cut the receiver media 26 after the first side of the printed image. The diverter 434 is then repositioned from the first position 435 to the second position 436 to deliver the cut receptor media 433 into a turning mechanism comprising a turning roller 438 and a guide 439. The cut receiver media 433 is then re-passed between the thermal print head 22 and the platen roller 46, where the opposite side of the cut receiver media 433 will now face the thermal print head 22 so that the second side of the image can be printed. To keep the printer size as small as possible, the turn roller 438 may need to have a relatively small radius. However, if the turning roller 438 is too small, it can have the adverse effect of introducing curl into the cut receptor medium 433 and creating scratches and other undesirable marks on the printed surface.

FIG. 8 shows a diagram illustrating a duplex thermal printer 700 according to a preferred embodiment. Receiver media 702 is supplied from a receiver supply roll 704. A supply transport roller 705 is used to transport receiver media 702 from a receiver supply roll 704. Receiver medium 702 is a thermal imaging receiver having a dye receiving layer coated on a first side and a second side of a substrate to enable duplex printing.

Two different media paths are provided in the printer: a print path 716 and a reverse path 726. A print path 716 transports the receiver medium 702 between the thermal print head 712 and the platen roller 714 for printing an image by selectively activating the thermal resistors 43 (fig. 2) to transfer dye from the donor ribbon 706 to the receiver medium 702. The donor tape 706 is supplied from the donor tape supply roll 708 and the used donor tape 706 is wound onto the donor tape take-up roll 710. The reverse path 726 provides a mechanism for reversing the side of the receiver media 702 facing the thermal print head 712.

The print path 716 includes a print path guide 718 for guiding the path of the receiver medium 702, and a main drive roller 720, a print path, and a feed roller 722. Similarly, the reverse path 726 includes a reverse path guide 728 and a reverse path transport roller 730. The use of guides and rollers to control the position of the receiver media 702 within the printer is well known in the art and will not be described in detail herein.

In the illustrated embodiment, both print path 716 and reverse path 726 include arcuate portions 717 and 727, respectively, to provide a "J-shaped" path. The use of curved portions 717 and 727 enables the printer size to be minimized by keeping the paper path more compact. In some embodiments, one or both of the print path 716 and the reverse path 726 may include a plurality of arcuate portions (e.g., forming an "S-shaped" path or a "C-shaped" path) to further reduce the size of the printer or control the location at which the printed image exits the printer.

The diverter 732 is pivotable about an axis 733 and is positionable in a first diverter position 734, a second diverter position 736, or a third diverter position 738. With the diverter 732 positioned in the first diverter position 734, the receiver media 702 is directed from the receiver supply spool 704 into the print path 716. The receiver media 702 is directed from the receiver supply spool 704 into the reversing path 726 when the diverter 732 is in the second diverter position 736. While the diverter 732 is in the third diverter position 738, the receiver media 702 is directed from the reversing path 726 into the print path 716. In the illustrated embodiment, the diverter 732 has a three-sided cross-section, where two top surfaces have a curved profile and the top angle at which the two top surfaces meet is circular. However, one skilled in the art of paper processing will recognize that other diverter shapes may alternatively be used to appropriately control the path of the receptor medium 702.

A cutter 740 is provided to cut a portion of the receiver media 702 from the receiver supply roll 704. A second cutter 742 is provided to trim the end of the receiver media 702 after the image has been printed. The cutters 740 and 742 may use the type of media cutting mechanism known in the art. In a preferred embodiment, cutters 740 and 742 use a rotary paper cutter mechanism having a wheel-shaped cutting blade that moves along a track across the width of receiver medium 702. In other embodiments, cutters 740 and 742 may use other types of media cutting mechanisms, such as paper cutter type cutting blades.

At the completion of the printing process, paper exit rollers 724 may be used to eject the printed image from the duplex thermal printer 700 through exit 744. A paper output tray (not shown) is typically provided into which the printed image falls as it is delivered out of the outlet 744.

The printer controller 748 is used to control the operation of the duplex thermal printer 700. The printer controller 748 may include, but is not limited to: a programmable digital computer, a programmable microprocessor, a programmable logic controller, a series of electronic circuits reduced to the form of an integrated circuit, or a series of discrete components. The printer controller 748 controls the thermal printhead 712 to record images onto the receiver medium 702. The printer controller 748 also controls other components, such as the various rollers and cutters 740 and 742 shown in fig. 8. The power supply 746 is used to supply power to the printer controller 748 and other electrical printer components. The duplex thermal printer 700 also includes various other components not shown in fig. 8, such as the standard components described earlier with respect to fig. 1.

FIG. 9 shows a flowchart outlining the steps involved in operating the components of the dual-sided thermal printer 700 of FIG. 8 to provide dual-sided printing in accordance with a preferred embodiment. Fig. 10A-10I show a set of drawings illustrating the operation of a duplex thermal printer 700 during a duplex printing process.

Step 800 of positioning the diverter into the first position is used to position the diverter 732 into the first diverter position 734. In some cases, the diverter 732 may already be in the first diverter position 734. In this case, step 800 of positioning the commutator into the first position does nothing. In other cases, the diverter 732 can be in another position (e.g., the second diverter position 736 or the third diverter position 738). In this case, the positioning diverter into the first position step 800 pivots the diverter 732 about the axis 733 to reposition it into the first diverter position 734. The step 805 of feeding the receiver into the print path is then used to feed receiver media 702 from the receiver supply spool 704 into the print path 716 by activating the appropriate drive rollers, as shown in fig. 10A. In this exemplary embodiment, the portion of the receiver medium 702 that is to receive the printed image is transported to the print path 716 to move past the dots of the thermal print head 712.

A print first side image step 810 is then used to print a first side image onto the first side of the receiver media 702. This is accomplished by moving the receiver medium 702 past the thermal print head 712, during which the thermal print head 712 applies a heat pulse to transfer colorant (e.g., dye) from the donor ribbon 706 to the first side of the receiver medium 702 according to the image data of the first side image, thereby printing the first side image. This is illustrated in fig. 10B. In this exemplary embodiment, the receiver media 702 is rewound onto the receiver supply roll 704 during the print first side image step 810. In other embodiments, the receiver media 702 may be moved in opposite directions during a printing operation.

Typically, the duplex thermal printer 700 is adapted to print color images. In this case, donor strip 706 typically comprises a series of donor patches, each donor patch having a different color of donor material as discussed with respect to fig. 3A. In this case, the print first side image step 810 will typically involve moving the receiver medium 702 past the thermal print head 712 multiple times for multiple passes of printing each time colorant is transferred from a donor sheet having a different color. Between each print pass, the receiver media 702 is repositioned so that the leading edge of the first side image is aligned with the thermal print head 712. Likewise, donor tape 706 is positioned such that the leading edge of the appropriate donor sheet is accurately aligned with thermal print head 712.

After the first side image has been printed, a rewind recipient step 815 is used to rewind the recipient media 702 back onto the recipient supply roll 704, as illustrated in fig. 10C. During this step, the receiver medium 702 is rewound to at least the point where the leading edge of the receiver medium 702 exits the diverter 732.

Then, step 820 of positioning the diverter into the second position is used to pivot the diverter 732 about axis 733 to reposition it into the second diverter position 736, as illustrated in fig. 10D. The receiver media 702 is then partially transported into the reverse path 726, as shown in fig. 10E, using a partially transporting receiver into reverse path step 825. In a preferred embodiment, the receiver medium 702 advances to a point where the printed portion of the receiver medium 702 moves past the cutter 740. Because thermal printing systems typically require at least a certain amount of margin to be maintained on the leading and trailing edges of the receiver media 702 to properly hold and control the receiver media 702 during the printing process, the receiver media 702 should be positioned such that the receiver media 702 can be cut with the proper margin size.

The cut receptor step 830 is then used to cut the receptor media 702 by activating a cutter 740 to sever the cut receptor sheet 750 from the receptor supply roll 704. Typically, the receiver medium 702 should be stopped before the cutter 740 is activated. The step 835 of fully conveying the receptor into the reverse path is then used to fully convey the cut receptor sheet 750 into the reverse path 726, as shown in fig. 10F.

Next, the step 840 of positioning the diverter into the third position is used to pivot the diverter 732 about axis 733 to reposition it into a third diverter position 738, as shown in fig. 10G. Step 845, which conveys the receiver into the print path, then conveys the cut receiver sheet 750 into the print path 716. By performing this series of operations, the second side of the cut receptor sheet 750 is now oriented to face the thermal print head 712, enabling printing of a second side image.

A print second side image step 850 is then used to print a second side image onto the second side of the cut receptor sheet 750. This is accomplished by moving the cut receptor sheet 750 past the thermal print head 712, during which the thermal print head 712 applies a heat pulse according to the image data of the second side image to transfer colorant (e.g., dye) from the donor tape 706 onto the second side of the cut receptor sheet 750, thereby printing the second side image. This is illustrated in fig. 10H. As discussed with respect to the print first side image step 810, the print second side image step 850 may involve multiple passes of printing to print a color image using a plurality of different colorants. In this exemplary embodiment, the cut receptor sheet 750 is moved in a downward direction during the print second side image step 850. In other embodiments, the cut receptor sheet 750 may be moved in the opposite direction during a printing operation.

As mentioned earlier, it is generally necessary to maintain at least a certain amount of margin on the leading and trailing edges of the cut receptor sheet 750 during the printing process. For many applications, it may be desirable for the final printed image provided to the user by the duplex thermal printer 700 to be a borderless print. Thus, an optional trim receptor end step 855 may be used to trim one or more ends from the cut receptor sheet 750.

In the illustrated embodiment, the cut receptor sheet 750 is conveyed toward the outlet 744 until the trimmed first end portion is extended beyond the cutter 742, as shown in fig. 10I. Then, the movement of the cut receptor sheet 750 is halted, and the cutter 742 is activated to cut off the first end portion of the cut receptor sheet 750. In a preferred embodiment, a waste bin (not shown) is provided into which the first end portion will fall when the first end portion is severed. The waste bin may be emptied periodically by an operator.

The cut receptor sheet 750 is then further advanced until the printed portion of the cut receptor sheet 750 (i.e., the portion of the cut receptor sheet 750 that will remain) extends beyond the cutter 742. Then, the movement of the cut receptor sheet 750 is halted, and the cutter 742 is activated to cut off the second end portion of the cut receptor sheet 750. The second end portion may then be allowed to fall into a waste bin.

The step 860 of transporting the receiver off the printer is then used to transport the cut receiver sheet 750 out of the duplex thermal printer 700, where the cut receiver sheet 750 may be provided to the customer or may be passed on to other finishing operations, such as a binding operation to form a photo album (which includes multiple printed pages). In some embodiments, the cut receptor sheet 750 may extend a substantial distance beyond the outlet 744 when the trim receptor end step 855 trims the second end portion of the cut receptor sheet 750. In this case, only the cut receptor sheet 750 may be allowed to fall into an output tray (not shown). In other cases, the cut receptor sheet 750 may be transported out of the duplex thermal printer 700 using transport rollers.

Those skilled in the art will recognize that many variations may be made to the exemplary embodiments discussed with respect to fig. 8-9 and 10A-10I within the spirit and scope of the present invention. For example, fig. 11 shows an alternative embodiment of a duplex thermal printer 900 that is the same as duplex thermal printer 700 of fig. 8, but with cutters 740 and 742 having been replaced with a single cutter 902.

The operation of the duplex thermal printer 900 is similar to that described with respect to the flowchart of fig. 9 of the duplex thermal printer 700. The primary difference relates to the positioning of the receptor medium 702 for the cleaving operation.

For the cleave recipient step 830, the recipient medium 702 needs to be further transported into the reverse path 726 before it can be cleaved. After the cut receptor sheet 750 has been severed, the remaining uncut portion of the receptor media 702 should then be rewound onto the receptor supply roll 707 until it exits the diverter 732 before the diverter 732 can move back into the first diverter position 734.

A cutter 902 is also used to perform a trim recipient end step 855. After the second side image has been printed, the cut receptor sheet 750 is directed back into the reverse path 726 until the trimmed first end portion extends beyond the cutter 902, at which time the cutter 902 is activated to sever the first end portion of the cut receptor sheet 750. The cut receptor sheet 750 is then further advanced until the printed portion of the cut receptor sheet 750 (i.e., the portion of the cut receptor sheet 750 that will remain) extends beyond the cutter 902, at which point the cutter 902 is again activated to sever the second end portion of the cut receptor sheet 750. The cut receptor sheet 750 may then be fed back through the print path 716 and out the exit 744.

The configuration of the duplex thermal printer 900 of fig. 11 provides a cost advantage over the duplex thermal printer 700 of fig. 8 due to the fact that one less cutter mechanism is required. However, print speed will typically be somewhat weaker due to the extra distance the cut receptor sheet 750 must travel during the process of trimming the ends. In an alternative embodiment, the exit 744 may be repositioned to the end of the reversing path 726 to minimize the distance the cut receptor sheet must travel after the trimming process is complete.

Those skilled in the art will recognize that numerous other variations may be made to the embodiments within the scope of the present invention. Fig. 13 shows an embodiment of a dual-sided thermal printer 905 that includes several optional features. One problem that can occur with web fed receptor media is curling caused by the media being stored on the receptor supply web 704. To reduce the amount of media curling, the receptor supply roll 704 may be turned such that receptor media 702 is fed from the receptor supply roll 704 as the receptor supply roll 704 turns in a clockwise direction. The receiver media 702 may then be pulled around the receiver de-hemming rollers 910 in an orientation that counteracts the hemming caused by the receiver media 702 wrapping around the receiver supply spool 704, thereby reducing some or all of the hemming. Guides 915 may be used to guide the receiver media 702 around the receiver decurl rollers 910 and to guide the receiver media 702 into the supply transport rollers 705.

The configuration shown in fig. 8 and 12 has the property that the receiver media 702 may extend partially out of the printer through the exit 744 during each print pass. This increases the risk of contaminating the receptor medium 702 due to dust and dirt introduced from the external environment. In addition, it can be confusing for the user when to see a partially printed image out of the exit 744. To alleviate these disadvantages, an upper diverter 920 may be used to divert the receptor medium 702 into an internal path 925 having an internal path guide 930. During a print run, the upper diverter 920 is positioned in a first raised position to direct the receiver media 702 into the internal path 925. Then, when printing has been completed, the upper diverter 920 may be repositioned to a second lowered position, directing the receiver media 702 toward the outlet 744. In this manner, the receiver media 744 does not exit the duplex thermal printer 905 until the printing process is complete.

In the illustrated embodiment of fig. 8, 11, and 12, the diverter 732 has a three-sided cross-section, where the two top surfaces have a curved profile and the top angle at which the two top surfaces meet is rounded. It will be apparent to those skilled in the art that various commutator configurations may be used to perform the desired function. Fig. 13A through 13F illustrate an exemplary set of commutator configurations that may be used in accordance with the present invention. Fig. 13A shows the same commutator 732 illustrated in fig. 8, 11 and 12. Fig. 13B illustrates a similar configuration of diverter 732 in which the top corner where the two top surfaces meet is not rounded. Fig. 13C illustrates a configuration of a commutator 732 having a simple triangular cross-section with flat faces. Fig. 13D illustrates a configuration similar to fig. 13A, in which rollers 760 are added at three corners of a three-sided shape, and the sides of the diverter 732 are provided as guides 762 for guiding the receiver media 26 (fig. 8). Roller 760 provides the following advantages: there will be a lesser amount of friction between the receptor medium 26 and the diverter 732. The rollers 760 may be passive or driven. Fig. 13E illustrates an alternative configuration in which the diverter 732 includes a conveyor belt 764 that follows a conveyor belt path around three rollers 760. The conveyor belt may be driven in either a clockwise or counterclockwise direction depending on the direction the receiver medium 26 is moving past the diverter 732. In some embodiments, the conveyor belt 764 can be a vacuum conveyor belt as is well known in the art. Fig. 13F illustrates an alternative configuration in which diverter 732 includes a paddle 736 that can be pivoted into three positions. In the first diverter position 734, the right side of the paddle 766 is tilted upward to deflect the receiver media 26 from the receiver supply roller 704 (fig. 8) toward the print path 716 (fig. 8). In the second diverter position 736, the paddle 766 rotates into a horizontal position so that the receiver media 26 can pass underneath in an undeflected path. In the third diverter position 738, the left side of the paddle 766 is tilted upward to deflect the receiver media 26 from the reversing path 726 (fig. 8) toward the printing path 716. Fig. 13G illustrates a similar configuration, wherein the paddle 766 has a curved profile.

The invention has been described in detail with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.

Parts list

18 thermal printer

20 Printer controller

22 thermal print head

22A thermal print head

22B thermal print head

26 receptor medium

30 donor band

30A donor tape

30B donor band

32.1 donor sheet set

32.2 donor sheet set

34.1 yellow donor tablets

34.2 yellow donor tablets

36.1 magenta donor sheet

36.2 magenta donor sheet

38.1 cyan donor sheet

38.2 cyan donor sheet

40.1 clear donor sheet

40.2 clear donor sheet

42 receptor driving roller

43 Heat resistor

44 receptor supply roll

45 ceramic substrate

46 platen roller

47 Heat sink

48 donor tape winding reel

50 donor tape supply spool

52 image receiving area

54 exfoliation member

56 idler roll

62 user input system

64 output system

68 memory

71 removable memory interface

72 hard disk drive

74 communication system

76 remote memory

80 sensor system

82 donor position sensor

84 receptor position sensor

86 movement sensor

88 driven wheel

90 heat sink

92 peeling member

94 pinch roller

96 micro-clamping roller

400 thermal printing system

410 duplex thermal printing system

420 two-sided thermal printing system

422 first position

424 second position

430 double-sided thermal printing system

432 cutter

433 cleaved receptor medium

434 commutator

435 first position

436 second position

438 steering roll

439 guide

700 double-sided thermal printer

702 receptor medium

704 recipient supply roll

705 supply conveyor roller

706 donor band

708 donor tape supply roll

710 donor tape winding reel

712 thermal print head

714 paper pressing roller

716 print path

717 arc part

718 print path guide

720 mainly driving roller

722 print path conveying roller

724 paper-out roller

726 reverse path

727 arc part

728 reverse path guide

730 reverse path conveying roller

732 commutator

733 shaft

734 first commutator position

736 second commutator position

738 third commutator position

740 cutting machine

742 cutting machine

744 outlet (from the vessel)

746 electric power supply

748 printer controller

750 cut receptor sheet

760 roller

762 guide

764 belt

766 Paddle

800 positioning a commutator into a first position

805 step of feeding a receiver into a printing path

810 printing a first side image

815 rewinding the acceptor step

820 positioning a commutator into a second position

825 step of partially transporting the receptor into the reverse path

830 cleavage of the acceptor step

835 step of fully transporting the recipient into the reverse path

840 the step of positioning the commutator into a third position

845 step of feeding a receiver into a print path

850 printing second side image

855 trimming recipient ends step

860 transporting the receiver out of the printer

900 double-sided thermal printer

902 cutting machine

905 double-sided thermal printer

910 receptor decurling roller

915 guide member

920 Upper commutator

925 internal path

930 internal pathway guide

L sheet pack leading edge

LED donor sheet front edge

LER receive zone leading edge

T-piece group trailing edge

TER receiving region trailing edge

Claims (16)

1. A roll-fed duplex thermal printing system, comprising:

a supply roll of thermal imaging receiver having a dye-receiving layer on a first side and a second side of a substrate;

a print path;

a reverse path;

a diverter pivotable about an axis into a first position, a second position, and a third position, wherein the diverter directs a thermal imaging receiver from the supply spool into the print path when in the first position, directs the thermal imaging receiver from the supply spool into the reversing path when in the second position, and directs the thermal imaging receiver from the reversing path into the print path when in the third position;

a thermal print head positioned along the print path;

a donor ribbon transported from a donor supply spool to a donor take-up spool by the thermal print head;

a cutter positioned between the diverter and the reverse path; and

a printer controller that controls components of the thermal printing system to perform the following sequence of operations:

positioning the commutator into the first position;

transporting the thermal imaging receiver from the supply spool into the printing path such that the first face of the thermal imaging receiver is oriented to face the thermal print head;

moving the thermal imaging receiver and the donor ribbon past the thermal print head during which the thermal print head applies a thermal pulse to transfer colorant from the donor ribbon onto the first side of the thermal imaging receiver to print a first side image;

rewinding the thermographic receptor onto the supply roll;

pivoting the diverter about the shaft to reposition it into the second position;

transporting the thermal imaging receiver from the supply spool into the reverse path;

using the cutter to cut a portion of the thermal imaging receiver that includes the printed first side image from the supply roll;

rewinding an uncut portion of the thermal imaging receptor onto the supply roll;

pivoting the diverter about the shaft to reposition it into the third position;

conveying the cut thermal imaging receiver into the print path such that the second face of the thermal imaging receiver is oriented to face the thermal print head;

moving the cut thermal imaging receiver and the donor ribbon past the thermal print head during which the thermal print head applies a heat pulse to transfer colorant from the donor ribbon onto the second side of the thermal imaging receiver to print a second side image; and

transporting the cut thermal imaging receiver out of the printing system.

2. The roll-fed duplex thermal printing system of claim 1 wherein one or both of the print path and the reverse path includes an arcuate portion.

3. The roll-fed duplex thermal printing system of claim 1 wherein the printing system is a color printing system, and wherein the thermal imaging receiver is moved past the thermal print head a plurality of times while printing one or both of the first side image and the second side image to transfer a plurality of donor materials from a plurality of corresponding donor sheets positioned in sequence on the donor ribbon, the donor materials including a plurality of corresponding different colorants.

4. The roll-fed duplex thermal printing system of claim 3 wherein the donor sheet comprises a transparent donor sheet for applying a donor material that provides a protective coating over the printed colorant.

5. The roll-fed duplex thermal printing system of claim 1 further including using the cutter to trim at least one end of the cut thermal imaging receiver after printing the second side image.

6. The roll-fed duplex thermal printing system of claim 1 wherein the diverter has a three-sided cross-section.

7. The roll-fed duplex thermal printing system of claim 6 wherein one or more of the three sides of the three-sided cross-section have a curved profile.

8. The roll-fed duplex thermal printing system of claim 1 wherein the print path includes guides for guiding receiver media through the print path and feed rollers for feeding the receiver media through the print path.

9. The roll-fed duplex thermal printing system of claim 1 wherein the reverse path includes guides for guiding the receiver media through the reverse path and transport rollers for transporting the receiver media through the reverse path.

10. The roll-fed duplex thermal printing system of claim 1 wherein the cut thermal imaging receiver is fed out of the printing system through an exit at an end of the print path or through an exit at an end of the reversing path.

11. The roll-fed duplex thermal printing system of claim 1 further comprising a receptor de-hemming roller, wherein the thermal imaging receptor is pulled around the receptor de-hemming roller in an orientation that cancels out a hemming of the thermal imaging receptor caused by the thermal imaging receptor wrapping around the supply roll.

12. The roll-fed duplex thermal printing system of claim 1 further including a second diverter positioned between the thermal print head and an outlet at an end of the print path, the second diverter having a first position and a second position, wherein when the second diverter is in the first position, the thermal imaging receiver is directed from the print path into an internal media path, and when the second diverter is in the second position, the thermal imaging receiver is directed out of the printing system through the outlet at the end of the print path.

13. The roll-fed duplex thermal printing system of claim 1 wherein the diverter comprises a conveyor belt looped around a plurality of rollers.

14. The roll-fed duplex thermal printing system of claim 13 wherein the conveyor belt is a vacuum conveyor belt.

15. The roll-fed duplex thermal printing system of claim 1 wherein the diverter includes a pivotable paddle.

16. The roll-fed duplex thermal printing system of claim 1 further comprising a second cutter positioned along the print path, wherein the second cutter is used to trim at least one end of the cut thermal imaging receiver after printing the second side image.